How to influence flux leakage on transformer?

in transformer emf is induced in primary or secondary due to self inductance & mutual inductance.flux is due to the self inductance is known as leakage flux,because it doesn't participate in transfer the energy from primary winding to secondary winding 

Regards

Hassan Qutb

In a Transformer, Core flux is the difference of primary flux and Secondary flux which are opposite to each other in direction and core flux depends on voltage and winding leakage flux depends on current and with out this leakage no transfering for energey from primary to secondary winding

 Transformers are therefore normally designed to have very low leakage inductance. Nevertheless, it is impossible to eliminate all leakage flux because it plays an essential part in the operation of the transformer. The combined effect of the leakage flux and the electric field around the windings is what transfers energy from the primary to the secondary.

In some applications increased leakage is desired, and long magnetic paths, air gaps, or magnetic bypass shunts may deliberately be introduced in a transformer design to limit the leakage flux.

But why to influence, other than only to minimize it....................

All Flux Produced in Primary winding must practically designed so that It must more Linked with secondary winding & leastly leaked ..............